Recovery of fat from fat containing material



March 25, 1958 1. H. CHAYEN 3 Sheets-Sheet 1 Original Filed July 18, 1951 F/GJ.

13mm. Hnmrs c/m YEN March 25, 1958 l. H. CHAYEN RECOVERY OF FAT FROM FAT CONTAINING MATERIAL Original Filed July 18, 1951 3 Sheets-Sheet 2 Inventor Ia RA EL f/A m1; c/m YEN March 25, 1958 1. H. cHAYEN 2,828,013

RECOVERY OF FAT FROM FAT CONTAINING MATERIAL Original Filed July 18, 1951 3 Sheets-Sheet 3 F/GB Inventor ISRAEL HARRIS C/mmv RECOVERY OF FAT FROM FAT CONTAINING MATERIAL Israel Harris Chayen, London, England, assignor, by

mesne assignments, to C. C. D. Processes (N. Y.), Limited, New York, N. Y.

Original application July 18, 1951, Serial No. 237,327,

now Patent No. 2,635,104, dated April 14, 1953. Di-.

vided and this application November 26, 1952, Serial 6 Claims. (Cl. 210-152) suet, gut fat and fat-containing meat than has been possible by prior processes.

' Although the process is applicable to substantially all.

United States Patent fat-containing materials it was developed as an improve-- ment in the degreasing of bones and the description of the process will be primarily directed to that operation.

The degreasing of bones is an important industrial operation, which is widely carried out, and the main purposes of which are firstly, to extract the maximum amount of fat, in a salable form andin the most economic manner compatible with the quality desired, and secondly, to prepare a degreased bone having as-low a content of fat and offensive organic impurities as possible and from which high quality glues and feeding meals or fertilizers can be produced. The degreasing operation is generally carried out by one of three processes known as dry rendering, wet rendering and solvent extraction. Theuse of each of these processes is, like the processes themfurther disadvantage is the high proportion of fat left in I the bones which is seldom less than 8% of the weight of the treated bones.

In wet rendering, the bones, either with or withoutprevious steam heating, are either simmered in hot water for periods of the order of from 5-8 hours, or digested for similar times with hot water and steam under pressure. The simmering process, when applied, for example, tofresh butchers bones containing 16% of fat, will generally extract about 10% of fat, the remainder being left in the bone. The prolonged simmering treatment has an adverse effect on the collagen, and the quality of the fat is also adversely afiected by the prolonged heating. The digester process gives a somewhat higher yield of fat, but the damage to the collagen is somewhat greater.

Glues and bone meals produced from wet rendered bones are inferior in quality to those produced from solvent extracted bones. v

The maximum known fat extraction is obtained by the the solvent from it, while thevapor in the bone is driven off by steam. When using this process, for which" a typical time is 22 hours, the fat yield from a typical 15% on the bone. The principal disadvantages of this process are the high capital cost of the necessary plant and the high fuel cost for operating it, the dangers from fire and toxicity of the solvents used, and the adverse effect of prolonged heating and solvent contamination on the fat and on the bones. Also, some of the fat is recovered in a tight emulsion with water and a difficult emulsion breaking operation must be carried out. 7 o

It will be noted that all of these processes are discon-' tinuous or batch processes in which both the bones and the fat are exposed to heat for prolonged periods, with the adverse effects to which reference has been made, while the discontinuousnature of the processes, and the prolonged heat treatments, increase their cost.

3 An object of the present invention is to provide an improved method of and means for degreasing bones have to be treated forthe separation from them of the contained'fat, .andthis is an important industrial operati on, which is carried out in many parts of the world.

, The method most generally used is that of hot rendering in which the material is heated in steam-jacketed,

vessels, generally fitted with paddles or the like to break it up during the heat treatment. When the rendering is complete, thefree fat is run oil from the denatured meat or proteinwhich is often termed greaves. These greaves generallycontain about 30% of their Weight'as fat,.which. figure can be reduced to from v12%20% by centrifuging j Sometimes, especially where the amount of. greaves is relatively. large, it is considered desirable still.

while hot.

further to reduce their fat content, in order to render them suitable for use as animal feeding stuffs, and this is usually done by a hot solvent extraction process, or by the use of expellers.

Q These processes are tedious, expensive and not very l efiicient, and the capital cost of the plant required is high. Moreover, the processes are all discontinuous or batch processes and the temperatures employed and the time required for the heat treatment have an adverse etfect on the quality of the fat.

An0ther object of the present invention is to provide anew and improved method of recovering fat from ani- "mal fat-containing products other than bones, which avoids the aforesaid disadvantages, and which is adapted to be carried out as a continuous process.

With respect to the degreasing of bones, the invention is based on the discovery that if fat-containing bones in a disintegrated condition are subjected to intense impacts car-percussive blows in the presence of water, which may be and preferably is at room temperature, the membranes which protect the fat cells in which the greater part of the fat is contained can'be disrupted, thus setting free the fat which may be readily separated in the form of a mixture of water and fat having a butter-like consistency. The mixture can be readily separated into fat and water, and the fat recovered. That is to say, the fat associated with some water will rapidly rise to the surface of the water in a settling operation, leaving the major portion of the water as a lower substantially fatfree layer. The disintegration of raw (i. e., fat-containing) bones by the intense impacts above described is difficult and inconvenient unless it is effected in the pres-,

ence of a liquid, preferably water. I prefer to carry out the improved process in such a way that the bones are disintegrated while in the .presence of and subject to the force of a vigorously moving body of water, preferably at: ordinary room temperature.

While I do nqt desire to be lintited to the u s e o f any particular type of plant, I have found that a convenient way of carrying out the newhprocess as a continuous one istcontin ou ht revised-rou h cru hed; nn a'nto a; ran dly rota ng hammer imillso quan ttr ate fi pneferahlyo p d l hicha st several ha e n s; h a' siutegrat boncaand; ater: r i pnt nuqus u isqhat d n nghz nez OKIIIQIQ ui ably imensie ed. rat ngs time a narat n t sek n ai ing s dtweet, eihet ei t llow d o; 1 a

hrou h h t a t n in sont nue sl .t emey dl c the bottomvby rnechauieal rneans such as a worrn The p "fi'd "eas ng bones in which bqnesin a dis-. nte ra e r d tf eri f e bjeqw 1 intense i a ts While "b'yl a bo dy of preferably cold ,water,

whl hjIthey. t 'eH w d s i l i pref ab y l wa r,

from lvvh ichfhe, treated bones and the fat which rises to fi e ater are s a ly; e n u dgv i 'oft iqi venti ii lp o ide a me h i s n Pan s i i ie girr ficrabl ou h c u hed? 130116 h V i v i elic o a body; oi iggrously moving'and'preferably cold wate after whicli'thej are allowedftosettle-in preferably" C01 at mm t t et st ae anq t e t ic Sii 0 a wft e;Wa eria e'zs r te y,r v

"knofherob ect' ofthe invention is to p'rovidea process 40 for'dg'reasing bones in=which preferably roughly crushed bones are fed in to a disintegrator mill, preferably of the rapidly {rotating hammer-mill type and are there disin; tegratdin 'the presence of a' quantity ofpreferably cold water; sufiicierit' to kep f the bones submerged; "whereby; the-'bories are disintegrate into small pieces while being; subjected to the 'foi'ce of a vigorously inoving: body'ot' water, the disintegrated bones an d waterbeing-discharged into" a sep ratingf'vsser -p referably already containing water-to the bottom from which th ey are removed while the {fab-which separates onJhe-surface of the wateris sepe arately remove d5 Another object of the inilentionsis to'provide a process of de'greasingcbones: which is carried 1 out-as a-continuous I processfthe: bones-and'waterbeing continuously fed to and dis'chargedfmnrthe-disintegrator mill while the disintegrated bones are continuously removed: from the separating yess ehand the fat :WhiC-h separates :onthesurface of tlietwatert iscontinuously removed therefrom:

Another objecLofithe invention is to provide a: processofitdegreasingL-bones in: which. the disintegrated; bones re- 4 moved:.fromathecoldnwatercseparating. vesselare treated irn another separating vesseltzcontainin'g hot waterg through which; the bonesQare allowed-1o fall- Ito the bottom from wh'ch:they are. removed tthe fatxwliich: separates 'on the surface .of .thezwaterbeing; alsorremoved. 1 V

The. optimum time for which ih disintegrated bones are subjectedato the forceof-t-he-vigqrously moving watershould be determined for a-givenkind' of-bonefin ;orderto ensure that the maxim-urn fat extraction'coupled with? a suitably-sized disintegrated "bone isy obtained When -1 bofiesfire in e et fi iit r e enswfi, fl tous ly movingbody of water the tirne pfthis tre a nt should be adjused to give a maximum fat extraction tos nysuitable esi n-t ge her with 5 i e libu er u s v bl s i Pr ss 35 4. fithcli wi h, a suitables sizes of... bone. particle, using. any, particular disintegrator. The time of treatment will depend on the origin and state of the bones before treatment, for example, the fat content, age, hardness and animal from which they are derivedand the purpose to which the ea e ed bone s tobeput-t- In accordance with the presentinvention, I'have also found that if soft fat products such as suet, gut fat and fatecontaining meatg fen example knackerameat and otter-,

anesuhjected, toaa treatment whiehraruptures they-membranes of the fat-containing cells, 'snchms'th'e intenseirnpacts o r percust iye blowsa described above while the eSOfia f t-gs in-,.;the presence of watere v he -fat.wvillr-beqreleased l-9% ti 1= l r t ill: orm ifikmixm rfil OfrfWfiiQR anditfat which can easily be removed from the majoriportion of the water and readily separated. As in vthe recovery of fat from bones, 'itis preferred that'the cell membranefiil l l 9P?! @tiQIl .ShQDld. carried out. in the presence offa relatively large volllmuroflyigomusly moving .yvater,

preferably cold water, 'Althougltflldo. notsdesir'e the, invention to be lirrjritedjin this' respect, I i at present also Pr f 1 r yut ihl I 'ope atiqn ini a h isp e r y swing 'beater'milliinto' which the softffdt prfilduots ,are fed,

preferably continuously, together with a relatively large volume -of preferably coldwater andffrom which} the.

said' products andwater' "are discharged; preferably,- con:v tinously, throughj suitably dimensioned gratings into ,a

separating-vessel"containingcold"water, on the surface of which 'the 'mixture of water and fat separates, and

from: which -itcan' easily' andcontinuously be removed.

The solid -residue which-"settles in the :vesselr'nay be collected, either a continuously or intermittently j and "may I be.-furthe'r' treated-br utilized as desired:

The-fat-eontent ofithesoft*fatproducts may vary within w-ide lir'nitspthussuet cancontain asmuch i as of fat and-inexceptional easesfeven moreyand very littleresidue, while inthe caseofisome-faficiontaihing products" thefat content may be'as 1ow asl5% u even-flower, while the residue-will be relat-ively large. lt wiil readily 15c understood,:therefo1 e; v that the detailsiofthe present process may be varied wit-hirt wide lirnits without-department from thezscopezof the invention.-.-=

The amounts of solid residues 'whieh -are separated' fromthe; animal rfateeontaining products yary according to the natureeofzthmproduct/treated but-ingenerahwill 'be small. Thusson allowing thlertreated productsto settlein a'watercontainingrvesselizia small; quantity of residue will settle" to thehottonu'o thewesselafrom which it may 13%16H10Y6d'7 the surface of the water generally contains a small-quan-- tityaofifiolid filirouszmateria-liwhich, however does not englgse the ,fattpatticles-zandsfrormwhieh-nearly all-"of the Y fat eagi;i fli yz'be;scparatedrhyiheating as-he1einafter--de--- scribed er Obit -1319f thetinvention; is, there-fore; to pro-- videgla rnethodcfqr ruQYering fat-ifrom soft" fat products in: ;wh1cl1. QfIi fat. products; are subjected to intense im--- Q- PI IJLenJ-Ihna membranes of: the fat-containing preferably colds watcngtfromuwhichthe fat which risest jtheu 'f se imemoved:

,while the gproductsrare surrounded-bye body; of I Another;9bic :theoinvention is to provide a method i -new r t-f said .pro ductseare su sofitfat; products a in which t the 0;, treatment gwhichcruptures the membranes of the fat-containing cells WhiltiithQSflidfi minsr ndn pr fer l d..-= ers n t; are ..fre. 1y;asus-.

pe sti rrou ded by: u h-,w en-af e :.which the-- pracluets a c a e t reual pl i .t .-.settle,r;. s iliuete si qmt whic nzthelt tr ris sut the st t separately; s

nplh t iee e vt nv nti nis t p p eep 'esss:

in which soft fat products are fed, preferably continuously, into a disintegrator mill, preferably of the rapidly rotating hammer-mill or swing beater type, and are then subjected to the action of the mill in the presence of a body of preferably cold water, whereby the membranes of the fat-containing cells are ruptured while the material is subjected to the force of the vigorously moving body of water, the contents of the mill including the' water being discharged, preferably continuously, into a separating vessel preferably already containing cold water, the residues being allowed to fall through the water to the bottom of the vessel while the fat which separates on the surface of the water is, preferably continuously, removed.

Other features of the invention will appear from the description which follows;

I will now describe in greater detail, and by way of example only, several methods of carrying out the process as Well as. arrangements of plant which are suitable for v the purpose, with reference'to the accompanying drawings, in which:

Figure 1 is a diagrammatic representation of plant suitable for carrying out the process in a simple form;

Figure 2 is a diagrammatic representation of plant employing hot and cold separators particularly suitable for the treatment of bone;

Figure 3 is a diagrammatic representation of a further modification of the plant;

Figure 4 is a diagrammatic view of a simple plant mer-mill; p t

. Figure 8 is a sectional viewof the'hammer-mill takenv on line 88 of Figure 7 with the rotor removed;

form of settling vessel; and

Figure 10 is a sectional view of the settling vessel taken on the line 10-10 of Figure 9.

The process as applied tobones in accordance with Figures 1 to 3, inclusive, will first be described.

Referring to Figure 1, the bones to be degreased, which should preferably be rough crushed to pieces of from one to two inches (2.5-5.1 cms.) in size, are continuously fed into the inlet 1 of a suitable high speed pulverizer or hammer mill 2, in which they are disintegrated in the presence of a substantial volume of rapidly moving water fed through pipe 3. Christy and Norris No. 2 /2 (18" by 12") standard type swing beater mill, fitted with A" (6.35 mm.) grids at its discharge outlet, rotating at a speed of 2,500 R. P. M. and continuously flushed, by means of a pump (not shown in Figure 1), with cold water at the rate of 400 gallons (1820 litres) per hour, gives excellent results when continuously fed with rough crushed bones at the rate of 8 cwts. (406 kg.) per hour. The gallons referred to throughout this application are British imperial gallons.

The grids should be so chosen, having regard to the nature of the bones, as to retain the larger pieces of bone for long enough to enable the fat-protecting membranes to be disrupted while at the same time delivering the bone of a size which is suitable for glue-making or tom '6 and containing cold water through which the bone: The ground bone is continuously a removed by means of worm conveyor.7. The fat sepis" allowed to fall.

It has been found that a Figure 9 is a diagrammatic plan view of apreferred arates and rises to the surface of the cold water as a fat-water mixture and is continuously removed by being allowed to How over weir 8, while the paddle 9 prevents floating fat from entering the worm conveyor 7. Surplus cold water, which also contains a little fat, is removed by pipe 10.

If the separated fat-water mixture is heated to about 94-98 C. and allowed to settle, the fat separates cleanly from the water as an upper layer and can readily be removed. The lower, or water layer, contains very little fat, which is easily recoverable-if desired; but some solid matter, mainly of a protein nature, settles out and may be recovered.

'It was foundtliat when using a rough crushed 'butchers bone of about 15% fat content, the wet disintegrated bone worm conveyor 7 is allowed to fall through the hot water to the bottom 12 of the vessel 11, from which it is again removed by a worm conveyor 13. I have found it ad vantageous to spray the bone in the conveyor with hot water fed through pipe 15 at or above the point where it emerges above the level of the hot water in vessel 11.

The vessel 11 is preferably so arranged and the speed of the worm conveyor so adjusted as to allow the bone, to be in contact with the hot water for a period of about 2 minutes. 7

A further quantity of fat will be found to separate as liquid fat on the surface of the hot water, from which it may be removed by flowing over weir 17, while the paddle 16 keeps the fat away from thebone. Surplus hot water is removed from the vessel 11 by means of pipe 18.

I have found that the fat recovery can be .further improved and the fat content of the ground bone still further reduced by arranging for the bone to be vigorously ag'itated for a short time with the hot waterin the vessel 11, before it is allowed to settle prior to removal from the vessel. In this case it may be convenient to provide a plurality of vessels, 11 into which the material from vessel 5 can be discharged, so'that while the bone is settling, after agitation in one vessel 11,'"it is being"dis-' charged into and agitated in another.

Water taken off through pipes 10 and/or 18 may be passed over separating pits to remove any fat and returned to pulverizer 1 together with fresh waterby means of .a pump (not shown).

In a further modification (Figure 3) the bone discharged from vessel 5 is passed together with cold water through pipe 19 to a centrifugal pump 20, to remove further bloody matter remaining in the bone as well as fur ther traces. of fat. In this case the 'materialfrom pump 2% is preferably discharged through pipe'21 into a second cold-water vessel similar to vessel 5, which delivers some further fat as a scum on the water, and a ground bone,

the fat content of which is somewhat lower than that f of the bone discharged from the vessel 5. This bone may then be treated in a hot vessel similar to vessel 11 (Figure 2) when a further small quantity of fat will be recovered and the resulting bone will be found to contain hammer mill, the grids used in the mill or mills should preferably" bet-oft lang ertgsize say about- /z inch; -1( 1:27. toiprgeizerrttheIdegreasechbone from becomin toq- In" general-s ll howeven; Itrpreferatalways'etocsu jectzz theabonettoza treatment insa cold separatingwessellaftcr, each treatment in the mill and to final treatment-Vin: a: hotwessel. v V a a It has been found in: then-case ofii-aL-gnound; boner-dis:- chargediromcyessel, 5..,(.after,=onermill treatment} iWithtafat-content of:3.6%, calculated'ion itstdryj ei-ght thisfat-t content;v was sreducedeto :1 .8 .%;..after av second treatment" in the :mill: followed by separationqimaz cold vessel and to about 0.5% after a third such treatment. 7 V V a For. t the tfurther .:understanding of, thee; invention, the following details of salstypicalttriahofihe, present .processs aretgiyensby waystof example onlyg. a

3.0 cwts. 1 5241 kg,')l,of ifreshvbutchen zbones (containing from..1 5l-' 16 by ,weig'htLotfat) were crushed to-rpieces of from 1 2} inches. (2.55. .cm.',) linssizefland continuously fed at the rate ofilQlcwts. (.SOSKgQQ perJhourtQa Christy and ,lNorrisl No- 2. /2; 'swi-n'g beaten mill, .ifi'ttedkwith A" (6.35 mm), grids ,;at the. discharge outlet; rotating at at speed ,of-IZLAOOI RI PL. M.. and..Qcontinuously flushedby means .off'al pump withcoldiwatert circulating atthe. rate. of"l,.0.00fgallons, .(4550' lli'tre s); per hour 7 The ground bone and Lwaters were discharged Ithrough s. the grids into a separating ryessels containing cold water from the, bottom of' which itwas continuously removedl by a worm conveyorato .the' second"separatingwessel containing hot water t he temperature ofQWhichwas main-- tained'attSS" C." Fforn thisyesselthe bones were, discharged again; continuously-,byfa worm conveyor for subsequent processing" s The water supply fo'r'the milFwasarranged as a closed. circuit while the overflow .of the water.containingj traces' offfat and .solid' "matter rwent finallyj to" settling ta'nks. This overflowris made 'up' by. the amount"of"water used; as'a spray to'washl'th'ej bone'and'also floatoff" the. fat in the" separating vessels; 7 V

The' bones' discharged from the first" separating] vessel had .a fat; content .of- 414% '7 (calculated on dry weight), while the degreased' bones discharged. fr'omthei secondseparating vessel had a fat content of 1.74%. (calculated on dry weight)"."

The fat reicoverediri-the trial'j'was' 12.5% .onraw mas trial; and it' was all" of" high. quality fandifexcellent. in appearance an'd'test. This fat; output could be increased" by about 2% 'onithesb'ones by"recovering th'eufat frjonr the solid'matter' and amixture'of'water'and fafcolle'cted from the settling tanks'.

I have found that, as a resulttofthe degreasingoperation being; carried .out wholly or rnainlywithcold water and requiring only a short time, the process according to" theinvention givesrise to .abone which has been substan tially de'gr eased and thecollagen ofwhich issubstantially, unchanged? Degreasedbones prepared by hitherto known methods'suffer from thegdi'sadvantage that at leasta part of'the collagen is changed ordegra'ded' and .a 'degreased' bone; the collagen of which Iis. substantially? unchanged (i. e., undegraded.)- isa'newproduct: The'new'product is moresconvenient for glue fanufa'cture than bones degreased by hitherto known methodsrand is also superior for use in, the preparation of feeding stuffs orfertilizersz The fat content lof;bones'degreased*by the method aecord ig to the invention varies according to the particular method of operation .used; but'in general I find that'where a single cold water-containing SCPfiI'3til'igjV6SS6l is 'used the fat.content of the.degreased'.bone isless-than"5%; when ta hot 'water containing,separating vessel, is 3 used *in, addition, the fatweontent-rof medegr eased'bone' is" less: than 2'.5 %"and usually less than 2%;1. e; separated fat "70 is also found to be superior to that-obtain'ed--'by the'hithertoknown methodsof-degreasing hones. 1

Very similaFapparatus-eanbe employedin the process as'applied-tcr soft fat productsz: Referring to -Figure:'.-4, l the soft fat products are fed continuously to the inlet 1 7 5 V i 7 8f. V of. any suitable high speed pulverizer: or hammer: milli which may beaof thessamettype described withrespecmo-s Fignressl. to, 3;.andrin whichhthey cambevsubjectemto the memhraneaupturing foreeinthe.presence rofasubstantial volnmetofnrapidlyz(moving water; fedfthroughlpipe 3; 1;, have foundathat: a-tChristy andtNorrisNo. .Z /zZ. standard typeswinggbeatersmill fittedawith A! (6.35.. mm. -gtids,t (not, shown).., at; its,:discharge,.:outlet;.andn rotating ,atwa ,i speed nfiabbut; 2,5 00; RsLP M. audnccntinuously v flushed, as] ,fornxamplei by: ,rneanspf apump withcoldtwater. at. thereto. of; .4-(10 rgallonsI..( l 820. litres). ,per hour,,gives,ex-. cell'nfresults' when continuously fed'withLtlie softjfatq productsamhe. ratetof 30:ewts..= (508 :k'g'.) per hour. 7

The gridsshould b'e so chosensas toretaintthematerialx for long. enough to enable. the membranesto .be. broken, but. insgeneraljl have foundth'e'stated size. tob'e suitable..-

The-mil-liis"arrangedfltofdischarge its contents through" pipe 4fin'to aseparating yessel 22; containirig cold water; Any solid"residu'es are allowd'to fallto the inclined; bottom .23 of -vessel 22, where they accumulate over the outlfeti24, from whiclithey can be removed'by ,washing as desired: The fat associated with 'Wate'r-whi'chiseparates on thesurfalcelof Ith'e'water antl'whi'ch'may contain fibrous tissue" is removed, either" continuously or discontinuously' by means of weir 25. V The water isremoved continuously by means" of'ia siphon pipe"26arrangedasilo'w as .possible in the vesselso as to .allow sufficient heighti'of water for, the fatt'o; separate, while attire same. time'being clear of thersludgie leveljlthe waterimay either be returnedjto the millbr run *todrain'. Thexrate'. of"flow of, the 'fat-. water foam over the"weirZSis'adjusted by alteringthe; heighLof the siphon pipe 26,.

Wlireiti's desiredto remove the solid -residues" con-. tinuouslyfrom the separating vessel 22,,the arrangementshown' in Figure 5 "may bensed'irr which the, solid residues are"'continuously removed by'meansofa worm-27i1 An alternative'arrangemenfhy which the'said residues are continuously removed andthewater from the separat ing'vesseli's 'returned to the mill 2tis'shown in "Figure 6; in this embodimentaprunp 2853s providedwhicl'r draws" waterfrorn-the' vessel 22 by"means of pipe 29 'andfeeds it to. the mill, which inturn dischargesthe-treatecr prod-- nets and Watento' the settlingyessel- 22 which is supplied with fresh water through pipe fitt to keepa fiowofwater and 'separatedfaf fiowin'g'over the-weir 25;" In'this'case I prefer to provide one or-rrroreyerticallydisposed baffl'es- 31inthevessel 22 leavin-g a'clearance "32' at-or near thedo'wer end; 1 and to' arra'ngej for' the mill to discharge into "one of-the-*compartments-thus formed 'Whilethe feed for the pump-28istaken through the pipe 29-from" that:compartment whielr contains the clearest watery This ensures that the feed 'water for the pump 28' will befairly 'free-of'soi-id=matter; 'which will mainly collect in the: other compartmentm lf thessepara ted fat is heated"to"about'94-98 C. and allowedto set-t-le it Willhe found'that clear fat=separatesas-an uppen layerorr'the Water-:- The lower; or water; layer containsvery* little-fat; which is easily recoverable iffidesired; butsome' solid'rn-atter, mainly of a-proteinl nature; settles out and can be recovered-Land used.

If the solid residues=recovered either from the fat Water mix'tnreaor the"separating vessel" should befound to-contain- -morea iat -than may be desired, -'theymay be reeirc ulated 'thiiough' the mill With more water and allowed to en-1e again; alternatively they may be dropped into and/Or -agitated wnn hot -Water-and jallowed to settle again;-in-=or ler2'tofacilitate-the separation of more fat As a" stillfirrthenaltemative; these: solids 5 maybe centr'i fuged either in their wetafor meas iobtainedor whilezbeing g sprayedacwitlrvsteanrmn hot .waten:

Thetsoiidsnohtainedeasza aiesnlt ;of ;the.;pnesent process; willcbezfoundirtor haye adow content; andathey; may be; driedrrtaudz-a-utilizedisfor, .any, suitable purpose 'suchnfom example; ,asz ether:preparationiwfwfeeding stuifs .andlon; fertilizers. V

7 It will be understood .that the foregoing description isgiven by way of example only and that various modifications may be made without departing from the scope of the invention. Thus, for example, the solid residues at the bottom of the separating vessel, which can be of any suitable design, may be removed in continuous or discontinuous manner.

The following details of some of the results obtained, which are given only as illustrations, will serve further to explain the nature of the invention:

I have found that a good quality suet, when treated according to .the present process and subjected to one settling operation in cold water, yielded 85% by weight of the suet in the form of edible fat. cold water used in the mill for grinding and circulation was small, but the small quantity of fat present in the water could easily be recovered by normal methods such as by heating and acid treatment orby treatment in a conventional, continuous centrifugal separator.

In the case of a sample of meat and fat, it was found that the yield of fat was calculated on the weight of the meat, while the solid residues represented 14% of the weight of the original meat, and these residues after a single cold treatment were found to contain of fat, calculated on the dry weight of the residue. This fat The loss in the content could be further reduced by a further circulation of the residue through the mill followed by a settling in cold water, or by a treatment in hot water as described discs is merely for the purpose of preventing breakage in the case of clogging of the mill or accidental feeding of metal or other non-disintegrable material, since hammers rigid with the rotor are entirely operative. The hammers will usually be relatively narrow, i. e., have a dimension axially of the rotor of the order of /2 to 1 inch, and the ends of the hammers will ordinarily be spaced a substantial distance from the inner periphery of the mill, for example, 1 inch in the case of a mill having a casing with a 2 foot diameter. A large mill will usually have a plurality of axially spaced circumferentially arranged rows of hammers and the roughly crushed pieces .of bone, when they enter the hammer mill casing through the chute 36, are subjected to intense int-- pacts by the hammerwhile they are surrounded by the relatively large amount of water fed simultaneously therewith. For example, with a rotor having a 22-inch diameter. measured between the outer ends of the harm mers and a rotor speed of 2,500 K. P. M., the ends of the hammers are traveling at a linear speed of approximately 14,400 feeLper minute. The pieces of bone are thus suddenly accelerated from a low velocity to a high velocity by a suddenly applied impact or percussive blow and thrown against the breaker block 43, where they are again subjected to impacts causing retardation or change of: direction of the pieces.

The linear speed of the hammers can be varied over a considerable range, for example, the mill referred to above operates satisfactorily though at reduced capacity at a rotor speedof 1,000 R. P. M., i. e., a linear speed of the ends of the hammers of approximately 5,600 feet 20 cwts. (1016 kg.) of raw material, consisting of beef suet and mutton suet; were continuously fed at the rate of 12 cwts. (610 kg.) per hour to a Christy and Norris No. 2% swing beater mill fitted with A" (6.35 mm.) grids at the discharge outlet rotating at a speed of 2,400 RxP. M. and continuously flushed by means of a pump with cold water at a rate of 600 gallons (2730 litres) per hour. 1

The ground material and water were discharged through the grid into a'separating vessel where the fat wa recovered from the readily separable mixture of fat and water.

The fat recovered in this trial was 86.2% by weight based on the raw material, and it was all of high quality and titre and excellent in color and odor.

Figure 7 illustrates a more complete plant which may be employed to continuously recover fat from either bones or soft fat products. In treating bones, the bones asthey come from the butcher or other source of supply may be delivered onto the belt conveyor '33 at a proper rate to supply the process and thereby fed into an apparatus 34 of any known or suitable type for reducing the bones to a size suitable for feeding into a hammer mill. r

This apparatus is preferably of the type which will crush or shear the bones into pieces ranging from 1 to 2 inches in size. The crushed bones discharged from the crushing apparatus may be received on a belt conveyor 35 and delivered thereby into the feed chute 36 of a hammer mill 37. A stream of fresh water, or water returned from subsequent steps of the process, or a mixture of both, may be simultaneously delivered into the feed chute 36 through a pipe or conduit 38 in an amount which is several timesthe weight of bones fed in an equal time.

The hammer mill 37 may be of a conventional type except as discussed below and may have a substantially cylindrical casing 38', in which is positioned a rotor 39 having its axis parallel to the axis of the casing. The rotor may include a plurality of discs 40, one of which is shown in Figure 7, secured concentrically on a driving shaft and having pivoted thereto a plurality of hammers 41. The pivoted connection of the hammers to the fore, appear to be between approximately 5,000 and 20,000 feet per minute for a mill of the type described and will be of that order for any type of impact aprunwithout rapid deterioration or destruction, since throughput increases with rotor speed. Practical considerations, however, dictate a maximum linear speed ofimpact to the neighborhood of 20,000 feet per minute. The useful range of linear speed of impact would, thereparatus useful in the present invention.

The roughly crushed bones are. broken into smaller pieces by the impacts they are subjected to in the mill. The lower portion of the cylindrical casing of the mill is made up of a grid 44 which may be formed of axially extending bars circumferentially spaced from each other to provide openings for escape of the bone par ticles. A suitable spacing between the bars has been found to be about inch, i. e., between approximately and /2 inch, and bone particles having a size corre' sponding to the openings in the grid or smaller are im-- mediately discharged from the mill. Larger sized particles are carried around the mill and repeatedly subjected to collisions with the casing and blows by the.

hammers until reduced to'a sufficiently small size to be discharged through the grid. 7

Bones contain relatively large pieces of tendon, however, and may contain pieces of skin, etc., which are not broken up in the hammer mill. As shown by the dash lines in Figure 8, the chute 36 may enter the mill at one end thereof, and at the other end of the mill a relatively large opening 45, for example, an opening 4 by 6 inches, may be provided for escape of the larger pieces referred to. In general, the bone itself is reduced to pieces or particles A inch in greatest dimension or less, but some larger pieces of bone find their way through the opening 45. Such large pieces, however, "are substantially free of grease, and it is apparent that it is not the reduction in size of the bone pieces which is the primary cause of the grease-releasing action of the mill.

Indeed, it is definitely disadvantageous to reduce the size of the bone particles to very small dimensions, for exam ple;..cell;size,.las; the resultantlarger. surface aareaqof .the bones ,causes the.,retention..of. a -.relatiuelyrlarge prppor-a tion "Bf fat;byi adherenceito. the..surfaces ofrlth e; bones. Preferably the particle size.ofnthe..degreased; bone..is.of. the order of.% inch; 5 It has beenfoundthat the presence..of.a.relatively large amount .of, water. is necessary for-effective removal .offIj grease from bones....In:the...absence.of .water, thelgrease v is not separated from thebones. Also :bonescontainirig,

a substantial. amount-of. fat cannot .be disintegrated. in

a hammer mill ."or othertypeof impact mill.in.the ab.-.. sence of water as=a practicalmatter, since-.the .mill clogs and .very large amountsofpower, inpract'icelunobtaine... able, are requiredto operate. the mill. v...Grease-contairi-Q. ing. bones havesubstantial. resiliency and are.difi1c'ult. to. shatter by impact blows. Apparently, the inertiaofthe water. surrounding the piecesofbone. adds..to..the inertia:-.v of. the pieces. to enable effective. application .of. the pact forces.

When water is introduced into the hammer mill, with120" the bones, theamount of power requiredto-drive'the rotor for-a given.rate..of feeding bones remains..high-. until they amountof water. approaches 3 to .S'timesthe. weight of .the bones. v,As-the amount of water. is in-, creased from approximately this amount .to approximate-i- 1y .7 times the weightof .the bones,.theamount..of.power to .drivetherotor continuesto .decrase. Asthe amount... of. water ,is further increased labove. about -7 times the. weight of the bones; the power required to...drive the... rotor remains fairly constant .upto .a .conditionwhere .the

- amount. of wateris approximately 30 timesrthe weightlof.

the..bones... ..The operative range of amount. of.water,=is,i therefore, approximately 3 'and 30 timesth'el weight .of the bone s and. the :range .of practical. loperatioriis be-,. tween: approximately 5 and- 15v times. the. .weight ..of,.'the..3 bones, theepreferred. amount being. about] timeswthe. weight. .ofjthefbonest. For example, ,very. satisfactoryoperationv has v..been .obtained with a.24.. by. 24'! hammer..mill=,of ithe .type above describcdQhaving' :arotor diameter. of.22.'. .between..the ends of the .hamrriers,..when. 40 the. rotor was .driven at 2,500 R.. P.M..and.'the feed was a 2 long .tons..(2032.kg.) of raw boneperhour and 3,000 gallons (13,650 litres) .of.,.,water per hour. 1 This .pro:. vided .a linear speedof. the. ends of .the .hammersof r approximately 14,400. feet per minute. ..The..weight..of: i water. fed. to ..the...mil1 in. a given time: was. approXimately;- 6.8] times the weight of bones.

The piecesrofhbone..discharged .fro'rn'v the -mill, after.. being. allowed to settle .in .water,-.show thatthe. intent... Whichwere present in the interiortof. the boneshave been.=. ruptured andthe grease.substantially'eornpletely removed therefrom... The. intense impacts .to which the..bones..are subjected have, .app arently. ejected the grease with. .violence froinlth. bone. .cells into. T1116 Water such Ltha'tthis. grease rem'ainssus'pended;in.the .Water and does notadhereto thelbone'ipieces; T he scrubbing action ofthewateriupon .1 the. .bone. pieces. ,due-..to .its vigorous movementthrough... the mill and the movement ofrthe .pieces through/the water caused by the. hammer. .blov'vsthereon also. assists in removing, the...grease from the..bones. The pieces of bone. discharged through thegrid 44 as well ,as'any large, pieces. of sinew. or. other; material discharged through! the opening; 45 .are flushed out of.the mill 'bythe vigorously moving stream of.water.. containing the .grease. in. suspen-... sion, 65

The'materials passed .through thermill are discharged... through a conduit. 46 into. the settling tank .47. Thebonepieces. asv well. as any...piece,s. .of .sinew; or .skin rapidly. settlello ,the....bottom oflth .tank 47 and aremremoved by. theiworm- .48. I If .lthe; water. is .cold, .lthe.;grease-isl not emulsified .into. the" .Water, so thatwitv rapidly rises to. the. surface. and..co1le'cts..as .athicksurface layer .of. butterr... likiei :consistency. .which'jis associated .ilwit-hta substantial 2 amount of ,water' and ialsol. (a small .amount. .oflfibrozus a. material; "Tliisfibfous material does not, however, em 7 12 closeirparticles Ofi'l tlie. grease since. .nearly.,all. .of lth'e grease..,may bereadiIyQ separatech therefromisby. a simple heatingandscreeningpperation. as described-below.-.

T lirpaddlefwheel A9Ipre'vents theflgrease.fromenteringa,

thelwormfifsoas :topr'event it from.being..removedfrom-..

the tank '47'with the bone particles-.- Inl a commercialp1ant,.it has.been found preferable to let/the grease and "theiwater inl'th'' tank 47"overflowuo'getherso that the water carries the thic'lo'laiyer" of grease out of the tank 47 and down thedisch"ar'g'e'chute' 50. The discharge chute 59 may empty into aseparating'tank'sl for separating thegreasefrdmtthe major portion 'of "the water. T lie g'rease continuesitofloat .flupon'" the 'surface-'of-the-' water in thetankSl ina thick layerand mayberemov'ew therefrombyabeitSZ 'haVing paddles 53' thereonwhich scrape the layer. of grease from th e"surfac'e -of thewater over-a weifinto a dischar-gewhute 54'; Tlie"water'rnay be discharged" from thedoivrportiori *of the tank 51"- through a constant level overflow"'pipe 53 into"a"d1s"-' charge' funnel 55 "along with any small amount 'of'protei'naceous'mater ial whi'eh-may-settle in the tank*-51.-''

As stated-=abov'e',-the grea'sdischirge'd from" the*'-tank'*' SI bYYthe-chute- 54 is of biittrdik;consistency and" is still associated" fwitha substantiahamount'of water; i. 'e., the-amount of watr ma-y" vary*from approxim'ately20% to'60% bf the total weight"ofthe -greasawater mixture.- Ini-zorder- 'to redut'ze th amount of -water'which mustbe heated-Whenthe grease is melted to separate it from the water, the grease is preferably first run through a 'dewateringimechanismi 56. This. mechanism m'ay" be similar to the squeezing apparatus employed 'in buttermanu factur'ing- ,to iremove=excess1water :from tbutter and' may includeaa worm (not shown); driven: from iany:suitable i=.-

- sourceofrpowen;throughifa':sprocket 57: Watenmawbe'ts discharged from Jone: endrmf thenapp'aratus 56 through I a COlldlllt: 58: into a discharge;funnel459,v .andiJ-grea'se having: its water. :conte'nt-:substantiallytreduced may .be.;-.1. discharged; 5 from the: other. end :of the apparatus .from

' a chute 60. Since the water discharged through the conduit-..-58.-"will ,usual1ycontainia substantial amount of grease, it is advantageously returned-to the settling tanks 51 -as indicated bytheidotted line fil forsettling of:- grease therefrom.

- Thegrease -rnay -be discharged: fromthechute 60 into a heating apparatus 62 .-which may be -of-.any..known' orsuitable type and is shown, forexampleyasa horizontal- .1 tank..provided -..with anaagitator. .63. and a steam jacket 64.. Ihe ag-itator '63.maybe drivenat a relatively low speed..just .'=sufiicient.tosensurer that-the grease and water 1 mixture delivered. into the-tankv 62 is" uniformly heated. Thegrease containinga small amount of water? is heated. in the ..tank-..6 2r.to a temperature.justabovathe melting; point.. .of the.- grease .and :imay. be Y. delivered: through ,a pipe tfi. ..onto..'sierie-66;@ Thealiquid. grease and small: amount of contained water passes through the sieve 66 and-.is .coll-ected .in.- a funnel 671 and "thereby delivered to --a conventional,.continuous .centrifugakseparatOr 68.- Theqsieve 66sremoves fibrous rproteinaceous material from 2 the...melted grease, .and-lthis materiahmayabe discharged-. through ;the,.funnel;69. Thernelte'dngrease isseparated from its'contained water in the. centrifugal; separator 68 and: dischargedf as the .-.lighter. efll-uentathrough a spout 70..into.a collecting .funnel. .71 frorr 1.;which itmay. be deliveredv into. suitable. containers-for rcooling. A- small 7 amount ..of ..water..,is discharged. as theaheavier effluent through 'a Spent 71 into a discharge funnel 73.

The temperature-employed to melttherfat will depend upon-the..typ.e,of fatbeingrecoveredfrom bones orotherfat'econtainingrmaterial andsneednot be higherathamthatrequired .ltowjust.irendertthe @fat; liquid..- This -.heating-..-.g operation=;shonld.-:be.tcarefully. distinguishedzfromn renal derin gr operationr .In....a renderingfl, operation .suflicient .2 temperatures and-.wtimet must. be vveniployedeto .brealc. then.

. walls'of. the fat..cells,iand .inQgeneral' a longtime ofa;

treatment or excessively high temperatures must be used both of which deleteriously affect the grease. in the present case, no fat cells exist and the grease is in condition to rapidly separate from the water as soon as the grease is melted.

The bones discharged from the settling tank 47 by the worm 48 willusually contain a small amount of grease superficially adhering thereto. These bones will also con tain pieces of tendon and may contain other material, such as pieces of skin, which also settle in the tank 47, and the bones containing such materials are preferably discharged into a second heated settling tank 74. A body of heated water at a temperature just above melting point of the grease is preferably maintained in the tank 74, and any suitable heating means such as steam jackets (not shown) or the introduction of live steam directly into the tank 74 may be employed to maintain such temperature. Thus the water temperaturemay range from 80 to 95 C. or even to 100 C. The bones and other solids associated therewith rapidly settle in the tank 74 While the grease adhering to the bones is melted and most of it rapidly rises to the water in the tank 74. Water is also introduced into the tank '74 as described below, and this water and the melted fat may be discharged therefrom over a weir and through a spout 75 onto a sieve 76.

Any fibrous or other solid, proteinaceous material, which floats and is carried in the melted grease and water, is retained on the sieve and discharged through the funnel 77. The melted grease and water pass through the sieve 76 and are collected in the funnel 78 and delivered to a settling tank 79. The settled water may be discharged from the settling tank 79 through a corn stant level overflow pipe 80 into a funnel 81. The melted grease still containing a small amount of water may be discharged from the top of the settling tank through a conduit 82 and delivered thereby to a conventional, continuous centrifugal separator 83. A small amount of water is discharged from the centrifugal separator as the heavier efiiuent through the spout 84 into a discharge funnel 85, and the melted fat is discharged as the lighter effluent through a spout 86 into the funnel 87 from which it may be delivered into suitable containers for cooling. While the melted fat containing a small amount of water from the tank 79 may be combined with that from the tank 62 and subjected to centrifugal separation in a single separator, it is preferred to keep the fat from the two portions of the process separate. It will be apparent that the fat discharged from the centrifugal separator 68 constitutes the major portion of the fat recovered in the process.

The bones and other materials settling in the tank 74 may be removed therefrom by a worm 88 and a paddle wheel 89 may be empolyed to prevent the fat from entering the worm 88. The bones discharged by the worm 88 are preferably washed by a spray of heated water delivered from a spray head 90 positioned over the discharge end of the worm 88. In general the bones may be put through the entire process except for drying in a few minutes, for example, 2 to 6 minutes so that the bones are subjectedto hot water treatment for a short time only, for example,1 to 3 minutes. The bones removed, from the tank 74 by the worm 88 will contain less than 2.5% grease and usually less than 2% grease on a dry basis but will be wet and still have'considerable water adhering thereto. These bones may be discharged onto a shaker screen 91 so as to remove adherent water therefrom, which water may be collected in a funnel 91'. This water will usually contain a small amount of bone and is advantageously returned to the tank 74 as indicated by the dashed line 92.

The bone and other material associated therewith progress down the screen 91 and may be delivered into a drying apparatus 92'. The drying apparatus 92' may be of'any known or suitable type, one suitable type being a 14 large drum containing an agitator with a plurality of rabble arms .(not shown) driven from any source of power through a pulley 93. A suitable drying gas, such as heated air or products of combustion may be introduced ,into the dryer through a conduit 94 and gas and water vapor discharged through a conduit 95. The dried bones which have preferably not been heated above 60 C. in the dryer may be dischargedfrom the dryer and from the process through a conduit 96.

While the settling tanks 47 and 74 may be of the type shown in Figure 7, in which the bones are removed from one end and the grease from the other, a preferred type of settling tank for separating the bones from the fat and water is diagrammatically illustrated in Figures 9 and 10. The tank 97 shown in these figures has a semi-circular end 98 with a flat,inclined bottom portion 98 and has its discharge worm 99 positioned at one side of the tank with a dividing partition 100 between the worm and the main portion of the tank. The position of the conduit 101 directly over the worm 99, for delivering material to be separated in the tank, is shown in Figure 10 and by dash lines in Figure) 9. The paddle wheel 102 is also positioned directly over the worm. The tank has its maximum depth at 103 and the bottom portion thereof slopesupwardly to the discharge weir 104 over which the fat and water or melted fat overflows into the discharge chute 105.

The water discharged through the funnels 73, 81 and will usually be sent to waste as this water is small in amount and contains very little total fat and solubles.

The water discharged from the tank 51 through the funnel 55 constitutes the major portion of the water employed in the, process and is advantageously reused. It contains a small amount of fat and a small amount of solid protein in suspension. It, however, contains a substantial amount of solubles, for example, blood albumin and other soluble proteins. The solid protetin may be removed by passing the water through a sieve, and most of the fat can be removed and recovered by further settling. Also the major portion of the solubles can be removed and recovered by steps which are not a part of the present invention, and the thus purified water can be returned to the mill 37 through the pipe 38 to reduce the amount of fresh water required. It is apparent that the present process is entirely operative, whether the water supplied to the mill is entirely fresh water or partly recycled water; and in this connection it should be mentioned that the water supply to the mill need not be through the chute 36 through which the bones are fed but may be through a separate conduit.

The fibrous proteinaceous material separated from the melted fat by the sieves 66 and 67, as well as any similar material separated from the water discharged from the settling tank 51 through the funnel 55, may be collected and dried in any desired manner and constitutes a valuable product. This material is predominantly protein but such material, particularly that from the screens 66 and 76, contains a substantial amount of fat, i. e., up to 45% calculated on the weight of the fibrous material. The total weight of such fibrous material is very small compared to the weight of fat otherwise recoveredin the process I such that the loss of fat is also very small. say, nearly all of the fat separates material.

The bones discharged from the process have their collagen content undamaged and contain substantially all of the colagen orginally present in the bones. This is in sharp contrast to all previous processes for the recovery of fat from bones. The periosteum adhering to the bone particles as well as the pieces of tendon adhering to or separate from the bones constitute the main glue-making or collagen-containing materials and are substantially in the condition found in fresh bones. On the contrary, the wet or dry rendering processes substantially completely destroy the collagen and even the solvent extraction proc- That is to from the fibrous essesresult inivery substantial;lossesofcollagen, and the recovered McoIIagenQisI iniua ..degr;aded eonditio'n. Aside" fromiemployinggthe bones as glue-making material's, thel bonesare of rnuchhigher quality for other uses since they V have. a muchhighr nitrogen content .thanthehones from previouslyemployed rendering processes. Higher quality.

bone mealsl foi: either. feedin'g ort fertilizerlpurposes can,

therefore, be produced fromathevbones Also,ith.faticon-.

tentsof the bones can beredu ced asldw ass-.015 by weight by the. process and will not exceed '2. when. the bones are subjeCted {to .the. heated water treatment? described above. s l Tli. fat content of the. bones. is, 7 therefore, sufii-l ciehtly low that. rancidity. problems: are 7 not encountered upon .storageof'hone meallinade therefrom.- B dnemeal made'f'r'm bonesucontaining more than 3 %I-fa't such as-the bones, from dry ,renderingb processesi rapidlyievelop 1 11 I offensive odor, upon storage 7 The grease. recovery ismuch higher. than-lthatirom wet it rend'ring or dry rendering 'processvand .istcomparable withthat. from solvent. I'eCOVCIY-yPI'OCESSCSR The recovered grease islof much higher quality, the" greaseflfrom fresh 'bu'tche'r bones being' almost whitehandi havingtza fatty acid content of. the recovered -greaseis: much-;1ower than that of" prior. rendering tprocesses. and the.tit1'-er and:

bleacha'hility is substantially: iI IiPIQVedN For purposes of'comparisonl-betweenthe presenttproc ess and the conventionally. employeddry rendering pm ess; thefollowingrepresent approximately theminimum results of a well "conducted processinlaccordance with the" present invention and -.approxiiriately:them aximum results of dry rendering processes. c In both casesplhe raw materials' are fresh butcher bones-- containing 15% fat'by weight onithe' raw bones.

Comparison-of yields a V 5 Present 7 Process" Percent I V Tallow recovered '(by welghton raw bones) 13 l Degreased: bone (by Weight, on raw bone's)1 Lossm Erocess (Moisture;tat proteim etm, byweight'onrew'bohes);;; s 32' ,7 35

' V w 100 Pretemwyletdsinribonestatbyzweiglit (m raw bones) 19. 25 16:60

Comparison 0.) nacoveredsboneiquality Present ,Drly Reiie' Process: daring i Percent- Fatcontentx by weight'on-'dry,bbnes):; t 2 Proteincontent lb tweight on dryihones) 5.; l r i 35 Comparisoniof rcoverea tallb'ui"qualityA I Present i Process Mdis'turaln'sblubl and restatement "hpercentJ;

weight on dry fatia Odor. -7. T

dominant ones' lravebeeniselected} bitt- L similar comparisons ca be made for"anyotherf'types of b'ones goats and/hogs. Bones from otheran'imalsgsuch as horse bones, whale bonesjetcl, are'also suitable sources; of supply' for the present process. The quality and type of grease recovered will of course depend upon "the" freshness of the bones and the type of animal from which the bones are obtained; but in general a'hi'gh'yieldof' grease of higher quality than that from'prior processes is" obtained. Substantially'the'same considerations apply to'" the recovery .of fatsfr'orn" soft fat products. That isto say-,the processis applicable to substantially all soft fat products, such as beef, mutton, and pork products, whale" blubber, etc", and again the quality of fat willdepend' upon the freshness and type of supply material.

Inemploying :th' apparatus'of'Figure 7 for recover ing fat from soft fat products, the bone crushing-1'appa ratus S-t'may .be' omitted That is to say, a plant em ployed for both' purposes, can have the soft fatprodiict's'" delivered onto' the conveyor 35 in'pieces of substantial" sizeso long'as the pieces are rsmall'enoughi'to" enter the hammer mill 37 throu'gh the chute 36: In general, the conditions of operationof' the hammer mill and the amount of water. fed thereto, onthelhasis of the weight of the material being fed, are substantially'the same" as in the case of recovering fa't'fro'rn-bone srl That is "to' sa'y; the amount of water may range from 3' to 30 'timesthe' weight of the soft fat and, prefer-ably'froiri 5 to 15 times, the weight of the soft fat. In the' hammer iniIL'the soft fat productsa're subjected tothe intense impacts'ahove describedwhile suspended in'or' surrounded-by 'wa'terg" and it appears that the connective tissue" enclosing the fat to' form the fat cells is violently .tornout of'the soft' fat products'to rupture the'cellsan'd' lea ve' the'fa't' sus pended in the wa'ter.--- Again; the fat, after the "contents p of the mill=are discharged intdthe' settling'ftaiikf47, tap;

idly rises to the surface'of the-water-in-the' form 'of a' thick butter-like layer associated with" a substantial" 7 amount of water; 'Also, thefat laye'rfromso'ft'fat'ptod ucts may contain considerably more fibrousrn'aterialthain is the case when bones 'are being treated-,although when treating high qualitysoftfat products, such as suet, sub stantially no fibrous-material appears in'the' fat 'discharged from the settling tank 51. Even when'p'resent, the fibrous material'does not enclose the'fa't, and a-siiri ple heating step will enable nearly all of' th'e melted fat to be readily-separated froni the fibrous material. The

, titre; a low 'freifatty' acid content and lowtolor" and containing-grease inlhdihgabonesffrom"other types. of

animats', usuatly hahdlii in'butcher shops, such as sheep,

rials: That=is t'o=say; thetemperature of'thefwater An' 'material"olrecting m' the bottom of thehettlifig" tank-47"ir1ayberemoveu by the worm r4sand' this mater'iall inayibe directly'dis'charged froiri th"pro'cess""or" additional fat canlbe"recovereditherefrorn 'by subjecting it to" a shert'tirtfeftre'aunem 'i'nheat'ed waterin the" settling tank 75? The" residual rn'a'terial" ma be dried i in any suitable" manner an'd'f constitutes an' "excellent mate; rial fo'rtfeeding' 'rnealsbrf rtiliz'ers'fi Inf'anyf'of nimpdincatibns "of theprocess'es "described 7 above; it is preferred tofemptoywater Whihis at 'a' teni peratur'e substantial beltiW'dhfeineltirig"temperature of inthehsett'ling' vesselsinwhichthe" d immune-major portion'offlthe Water :antl -from the residues of the fat 'containingmate the fat preferred operation may vary from just, above the freez ing-V- temperature to-just =-below:- ca; 'tempe'ra'tnre-swhieh will melt the fat-i Th-us waterat: the ordinary temperatures of natural s ourees or of municipalwater. supplies or Wa'-' i I ten atroorn'temperatureare satisfactory; Such water is" referred to herein as cold Water as distinguished from 17 water substantially above room temperature, i. e., above 25 C. This enables a high recovery of a fat of soft butter-like consistence which may, if desired, be worked to remove a portion of the water associated with the fat before the fat is melted. The advantage of being able to employ water at the temperature of usual sources of supply is apparent, as expensive heating of the water is thereby avoided and the only water it is necessary to heat is a small amount used to wash the bones or other residual products after the initial separation of the fat and the small amount of water contained in the fat during melting thereof.

So far as actual operativeness of the process, however, it is possible to employ Water at a temperature above the melting point of the fat up to approximately the boiling point of water in the mill and in the initial separating steps. By so doing an effective separation of fat from the bones or other fat-containing material and from the water can be obtained in a single settling operation. That is to say, the fat is melted as rapidly as it is released from the bones or other fat products and is scrubbed clearly therefrom by the relatively moving heated water. No subsequent washing operation of the bones or other residual material is required to reduce their fat content to a low value and the separated melted fat requires only clarification. The disadvantage of such process is, however, the expense of heating the large amount of water required during impact treatment of the fat-containing material and this disadvantage will ordinarily outweigh the advantages of eliminating the other steps of the preferred process. The process employing heated water does, however, have important advantages over prior fat recovery processes in that a higher recovery of higher quality fat is obtained and in the case of treating bones, a higher nitrogen content and an undamaged collagen content is obtained. One reason is that the materials are subjected to the hot water for a brief period of time only, for example, 1 to 3 minutes and the temperature does not exceed the boiling point of water.

One of the important features of the invention appears to be that the fat cells of either bones or soft fat products are ruptured mechanically by percussive blows or intense impacts, while freely suspended in or surrounded by water so that the impacts not only rupture the fat cells but forcibly eject the fat therefrom into the surrounding water. The resulting relative movement between the fatcontaining material and the water also appears to scrub the fat therefrom. The fat is thus mechanically separated from the bone cells and connective tissue of either the bones or the soft fat products and is substantially prevented from adhering thereto by intervening water films. While the hammer mill above described is a convenient and effective way of providing the impact treatment and is a commercially available device, it is entirely possible to accomplish the same result with various apparatus. For example, instead of employing moving hammers to strike the relatively stationary pieces of fat-containing material while surrounded by water, the pieces of fat-containing material along with the requisite amount of water can be fed to the interior of a rapidly rotating centrifugal thrower and violently thrown therefrom through radial passages against stationary or reversely moving projecting elements or bars so as to produce the intense impacts and the relative movement with respect to the water.

The impact treatment while the material is suspended in or surrounded by water is to be distinguished from processes involving grinding, slicing or pounding treatments in which the material is compressed or sheared between two or more elements or surfaces irrespective of whether water is present. In such treatments the fat issmeared onto or pressed, into the non-fat material and is. diflicultly separated therefrom even though a majority of the fat cells may be broken. The treatment of the present invention is also to be distinguished from operations merely involving agitation of the fat-containing materials in water, either with or without heating. In such operations, if the agitation is sufiicient to rupture the fat cellsand release the fat, it also produces a difficultly separable tight emulsion between the fat and water.

Although the fat and water is subjected to considerable agitation in the impact treatment ofthe present inven tion, no emulsion between the water and fat is formed and the fat-containing a relatively small amount of easily separable water quickly separates from the major portion of water whenthe material discharged from the mill is subjected to settling. The water in the separated fatlayer appears to be mostly in the form of films of water surrounding relatively large particles of fat and is not emulsified therein, as a substantial portion of the water can be removed by a mere squeezing operation. 'While some fibrous material also floats and appears in the fat layer, it doesnot surround the fat particles, since a mere heating operation with or without a squeezing operation to decrease the water content of the fat layer enables nearly all of the melted fat to be readily separated from the fibrous material. Since the recovered fat is of higher quality and the recovery of fat is greater than that previously obtained in rendering operation and since in the case of treating bones the bones are also of higher nitrogen content and contain substantially all of the collagen of the bones in undamaged condition, it is apparent that I have provided an improved process of recovering fat from animal materials containing fat.

While the process of the present invention was developed forrecovery of fat from animal material containing fat, it is apparent that it is applicable to various vegetable materials containing solid or liquid fat. Thus various seeds and beans, such as cotton seed or soyabeans contain liquid fat or oil in cells. The impact treatment of the present invention in the presence of water ruptures such cells and ejects theoil into the water in the same manner as with animal products. The resulting relative movement with respect to the water also scrubs the fat from the residual products so that the fat or oil is suspended in the water and thus separated from the wet residual products. Such oil or fat collects upon the surface of the water during a settling operation with the major portion of the residual substantially fat free mate.- rial in the lower waterlayer.

In the above specification and the appended claims, the term fat is employed as a generic term to mean either fat which is solid or semi-solid at usual ambient temperatures, or fat which is liquid at such temperatures.

This application is a division of my copending application Serial No. 237,327, filed July 18, 1951, now Patent No. 2,635,104, which in turn is a continuation-in-part of my copending applications Serial Nos. 166,573 and 166,574, both filed June 7, 1950 and both now abandoned.

I. claim:

1. Apparatus for recovering fat from cellular fat-containing materials, whichcomprises, a plurality of impact elements, acasing enclosing'said impact elements, means for continuously feeding pieces of said material into said casing, means for continuously feeding into said casing a stream of liquid in an amount at least three times the weight of the fat-containing materials, means for producing relative movement between said pieces of material and said impact elements of approximately 5,000 to 20,000 feet perminute so that the fat-containing cells in said materials areruptured by intense impacts delivered thereto while surrounded by said liquid thereby to release the fat and scrub the fat from the residues of said pieces by relative movement between said residues and said liquid, aconstantly open discharge opening having a grating covering the major portion thereof and provided with openings through which the resulting materials are continuously discharged, a vessel for receiving the resulting materials discharged through said grating, and means for separately delivering residual disintegrated material and a material high in fat'content from said vessel.

2. Apparatus for recovering fat from cellular fat-containing materials, which comprises the combination of, a hammer mill having a rotor provided with a plurality of impact elements on the periphery thereof, and a casing for said rotor having an inlet conduit leading into the upper portion thereof and a discharge grating, with means for continuously feeding pieces of said material into said casing through said conduit, means for continuously feeding a stream of water into said casing in an amount several times the weight of the fat-containing materials, said rotor turning at a high speed so that the fat-containing cells in said materials are ruptured by intense impacts delivered thereto while surrounded by water thereby to release the fat and scrub the fat from the residues of said pieces by relative movement between said residues and water, whereby a mixture containing residual disintegrated material and fat suspended in water is continuously discharged from the mill through said grating, a settling vessel receiving the mixture discharged from said mill through said grating, whereby fat collects as an upper layer on the surface of said water, and means for separately delivering said upper layer and said water from said vessel.

3. Apparatus for degreasing'bones, which comprises the combination of, a hammer mill having a rotor provided with a plurality of impact elements on theiperiphery thereof and a casing for said rotor spaced from said impact elements and having an inlet conduit leading into the upper portion thereof and a discharge grating, with means for continuously delivering pieces of said bones into said casing throughisaid conduit into thepath of said impact members when said rotor is rotated, means for continuously feeding a stream of water into said casing in an amount several times the weight of the bones, means for rotating said rotor so'that thev fat-containing cells in said bones are ruptured by intense impacts delivered thereto while surrounded by water thereby to release the fat from said bones and separate the fat from the residues of said bones by relative movement between said residues and water, whereby a mixture of comminuted bone and fat suspended in water is continuously discharged from the mill through said discharge grating a settling vessel receiving 'the mixture Of comminuted bone, water and fat discharged through said grating, whereby said comminuted bone settles in said water and fat collects on the upper surface of said water, and means for separately removing said comminuted bone and fat from the major portion of said water.

4. Apparatus for recovering fat from animal bones containing said fat, which compris'es,'a plurality of impact elements, a casing enclosing said'elementsand provided with constantly open inlet and discharge openings,

means for continuously feeding pieces of said bones into said casing through said inlet opening, means for simultaneously-continuouslyfeeding water into said casing and into contact with the pieces therein at a rate several times the rate of'feeding said pieces ona weight basis, means for producing relative movement between said pieces in said casing and said elements of the order of 5,000 to 20,000 feet per minute so that the fat-containing cells in said, bones are ruptured by intense impacts delivered thereto while surrounded by water thereby to release, the fat and separate the fat from the residues of said bones by relative movement between said residues and 'said water, said casing having agrating extending across said discharge opening through which the resulting mixture containing said smaller piecesof bone and said fat suspended in water iscontinuously discharged, a settling vessel receiving the discharged mixture in which saidsmaller pieces of bone's ettle in said water and: alayer of fatty materialcollects on the upper surface of said water, a

conveyor for removing the settled bone from, said vessel, and separate jmeansifor discharging said ;fatty material and water from said vessel. 1 1 r 5. Apparatus forrecovering fat 'from'material containing fat in cells in said material, which compriseathe combination of,a hammer mill having a rotor provided with a plurality of impact elements on the periphery thereof, and a casing for saidrotor having an inlet conduit connected to the upper portion thereof and a constantly open discharge openingprovided with a discharge grat ing covering the major portion of said opening, said rotor turning at a high speed to impart a linear speed to said impact elements ranging between approximately 5,000 and 20,000 feet per minute, means for continuously feed ing pieces of said material into said casing'through said conduit and into the paths of said impact elements, means for continuously feeding water into said casing and into contact with the pieces of material thereinjat a rate several times the rate of feeding of said pieces'on a weight'basis so that said pieces are subjected to intense impacts while the material is suspended in water whereby the cells in said material are ruptured to release said fat and the fat is scrubbed from the residuesof said pieces by relative movement between said residues and said water and a mixture of fat suspended in water and residual cellular material containing water is continuously discharged through said grating, and means for separating said fat 7 and residual cellular material from each other and from themajor portion of said water by difference in specific gravities. v,

' 6. Apparatus for recovering fat from material; containing fat in cells in said materiahwhich comprises, the combination of, a hammer millhaving a rotor provided with a plurality of impact elements on the periphery thereof, and a casing for saidrotor having an inlet conduit connected to the upper portion thereof and a constantly open discharge opening provided with a discharge grating, means for driving said rotor to impart a linear speed to said impact elements ranging between approximately 5,000 and 20,000 feet per minute, means for continuously feeding pieces :of said-material into said casing through said conduit and into the paths of said impact elements, means for continuously feeding liquid into said casing and into contact with the pieces of material therein at a rate several times the rate of feeding of said pieces on a weight basis so that said pieces are subjected to intense impacts while surrounded by water whereby the cells in said material are ruptured to release the fat and the fact is scrubbed from the residues of, said material by relative movement between said residues and the water and a mixture of fat, liquid and residual cellular ma- References Cited in the file of this patent UNITED STATES PATENTS I 188,429 Smith Mar. 13, 1877 189,541 Andrew Apr. 10, 1877 231,555 Gastard Aug. 24, 1880 287,862 'Robison Nov. 6, 1883 668,211 Powter Feb; 19, 1901 2,105,759 Stevenson Jan. 18, 1938 2,189,418 Finney Feb. 6,- 1940 2,196,991 Jacobs et al Apr. 16, 1940 2,281,590 Newton May 5, 1942 2,281,609 Walter May 5, 1942 2,443,274 Schroeder June 18, 1948 2,635,104 Chayen Apr. 14, 1 953 7 FOREIGN PATENTS 3,357 Great Britain 1909 8,397 Great Britain 1912 

1. APPARATUS FOR RECOVERING FAT FROM CELLULAR FAT-CONTAINING MATERIALS, WHICH COMPRISES, A PLURALITY OF IMPACT ELEMENTS, A CASING ENCLOSING SAID IMPACT ELEMENTS, MEANS OR CONTINUOUSLY FEEDING PIECES OF SID MATERIAL INTO SAID CASING, MEANS FOR CONTINUOUSLY FEEDING INT SAID CASING A STREAM OF LIQUID IN AN AMOUNT AT LEAST THREE TIMES THE WEIGHT OF THE FAT-CONTAINING MATERIALS, MEANS FOR PRODUCING RELATIVE MOVEMENT BETWEEN SAID PIECES OF MATERIAL AND SAID IMPACT ELEMENTS OF APPROXIMATELY 5,000 TO 20,000 FEET PER MINUTE SO TAHT THE FAT-CONTAINING CELLS IN SAID MTERIALS ARE RAPTURED BY INTENSE IMPACTS DELIVERED THERETO WHILE SURROUNDED BY SAID LIQUID THEREBY TO RELEASE THE FAT AND SCRUB THE FAT FROM THE RESIDUES OF SAID PIECES BY RELATIVE MOVEMENT BETWWEN SAID RESIDUES AND SAID LIQUID, A CONSTANTLY OPEN DISCHARGE OPENING HAVING A GRATING COVERING THE MAJOR PORTION THEREOF AND PROVIDED WITH OPENINGS THROUGH WHICH THE RESULTING MATERIAL ARE CONTINUOUSLY DISCHARGED THROUGH SAID GRATING, AND MEANS FOR MATERIALS DISCHARGED THROUGH SAID GRATING, AND MEANS FOR SEPARATELY DELIVERING RESIDUAL DISINTEGRATED MATERIAL AND A MATERIAL HIGH IN FAT CONTENT FROM SAID VESSEL. 